Signatures of a ferro-Josephson effect in twisted graphene
Abstract
When a spin-polarized current is driven across a magnetic domain wall, the resulting spin-transfer torque may, beyond a critical threshold, set the wall's moments into precession. This precession modulates the Berry curvature experienced by electrons traversing the wall, producing an electromotive force that is topological in nature and proportional to the precession frequency, mapping precisely onto the DC Josephson effect and leading to the name ferro-Josephson effect. We report signatures consistent with this effect in a twisted graphene van der Waals heterostructure, where spin and valley textures are linked by exchange, Hund's coupling, and spin-orbit interactions. Tuned to fillings where the isospin degeneracy is spontaneously broken, the samples develop a sharp peak in the longitudinal resistance within a fraction of a millitesla of B∥=0---a peak that disappears as the current is reduced toward zero. In differential resistance the feature resolves into sharp resonances that disperse with B∥ on microtesla and picoampere scales. We argue that these arise from the current-driven precession of spin-domain-wall moments, in competition with the in-plane anisotropy set by a minuscule applied field, and that they establish nonlinear transport as a sensitive probe of isospin domain-wall dynamics at energy scales far below kBT.
Related
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- Nonlocal Josephson coupling and current redistribution in a large-area graphene multiterminal Josephson junction
- Evanescent-mode Casimir-Josephson force and gate-controlled resonances in ballistic graphene Josephson junctions
BibTeX
@misc{su2026signatures,
title = {{Signatures of a ferro-Josephson effect in twisted graphene}},
author = {Ruiheng Su and Zhenxiang Gao and Christopher Coleman and Manabendra Kuiri and Dacen Waters and Kenji Watanabe and Takashi Taniguchi and Matthew Yankowitz and Nemin Wei and Chunli Huang and Allan H. MacDonald and Joshua Folk},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2608.25257},
eprint = {2608.25257},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.25257},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Signatures of a ferro-Josephson effect in twisted graphene
AU - Ruiheng Su
AU - Zhenxiang Gao
AU - Christopher Coleman
AU - Manabendra Kuiri
AU - Dacen Waters
AU - Kenji Watanabe
AU - Takashi Taniguchi
AU - Matthew Yankowitz
AU - Nemin Wei
AU - Chunli Huang
AU - Allan H. MacDonald
AU - Joshua Folk
PY - 2026
DA - 2026/09/06
PB - arXiv
DO - 10.48550/arxiv.2608.25257
UR - https://arxiv.org/abs/2608.25257
AB - When a spin-polarized current is driven across a magnetic domain wall, the resulting spin-transfer torque may, beyond a critical threshold, set the wall's moments into precession. This precession modulates the Berry curvature experienced by electrons traversing the wall, producing an electromotive force that is topological in nature and proportional to the precession frequency, mapping precisely onto the DC Josephson effect and leading to the name ferro-Josephson effect. We report signatures consistent with this effect in a twisted graphene van der Waals heterostructure, where spin and valley textures are linked by exchange, Hund's coupling, and spin-orbit interactions. Tuned to fillings where the isospin degeneracy is spontaneously broken, the samples develop a sharp peak in the longitudinal resistance within a fraction of a millitesla of B_∥=0---a peak that disappears as the current is reduced toward zero. In differential resistance the feature resolves into sharp resonances that disperse with B_∥ on microtesla and picoampere scales. We argue that these arise from the current-driven precession of spin-domain-wall moments, in competition with the in-plane anisotropy set by a minuscule applied field, and that they establish nonlinear transport as a sensitive probe of isospin domain-wall dynamics at energy scales far below k_BT.
ER -